On Wed, Feb 07, 2001 at 01:32:00PM -0700, Ronald G Minnich wrote:
>
>
> Each item on the list is marked as M (mandatory), R (recommended),
> O (optional), A (architecture dependent, not needed on all systems),
> C (chipset dependent)
I have made a few notes from the embedded-system point of view.
> Assembly startup:
> M Reset jump to start of LinuxBIOS
> M Ensure CPU is in sane state (e.g. Purge I Pipeline, etc.)
> A Put CPU into protected virtual memory mode
> O Enable serial port debugging print
> O Enable debugging prints to console graphics
> O Memory test
I presume that mixed in here somewhere was basic chipset init, enough to
get RAM turned on? That'd be chipset-dependent, of course.
> M Set up C environment
> M Jump to C code
>
> Hardware startup:
> A Configure Cache. Needed here for speed.
> A Processor-dependent steps that are required, e.g. microcode patch
> M Init C display variables. Required before printk()
> M Init malloc memory pool
> O Display processor internal details of value (e.g. intel cpuid)
> O Pick a PCI method if you need to init PCI
> M Size memory so you can tell Linux
^
Embedded systems may prefer this be optional so memory-size can be
hardcoded and forgotten. Wouldn't this also be arch- or chipset-
dependent?
> A Re-config the cache so that it caches all or memory
> O Configure PCI bus
> A Mainboard fixup
> C enabled extended NVRAM access
> A Handle extended machine state (e.g. MTRR)
> C Enable keyboard
> C Enable floppy
For obvious reasons, embedded folks would like to see this be optional.
> A Enable tables that Linux uses on startup (e.g. SMPBLOCK)
> M Set up IRQ tables for Linux
For simplicity, I'd prefer this be optional. With no capability for
hot-plug devices, I'd rather have interrupts get set up once and left
alone. That assumes, of course, that PCI config has calls to a
chipset/mainboard-specific irq-routing function. (don't remember if
linuxbios has that capability right now).
> R Enable interrupts
> O Final Mainboard Fixup
> A Final L2 Configure
> M Call non-hardware-dependent linuxbiosmain()
>
> Kernel startup:
> O Banner
For debugging and development reasons, I have stuck a check for keypress
here, along with a debugging menu that allows me to fiddle with things
from cache setup to kernel params. I did this stuff for my own needs, but
it turned out to be such a useful item that other folks might find some
use for it. I know you cluster guys hate using the console, but it's
pretty nice for debugging and development in my embedded system. That
might affect the location of kernel parameter setup below. Example: what
if a particular driver suddenly starts locking up the system on boot? It
sure is nice to pass "1" (means start in runlevel 1) to the kernel as a
parameter, to get yourself into the system to fix things...
> M gunzip setup
> M gunzip
> M Linux parameter setup
> (mistake! move me!) APIC setup
> M Jump to Linux
